Liquid fuel



Patented Aug. 17, 1937 LIQUID FUEL Arthur A. Roberts, London, England; Arthur Roberts and Clifiord Wilbur Smith atrators of said Arthur A. Roberts, deceased No Drawing. Application July 17, 1934, Serial No. 735,711. Renewed January 11, 1937. In Great Britain June 23, 1933 The present invention relates to improvements in liquid or mobile fuels, such as oil or stabilized mixtures of carbonaceous materials, such as coal with oil.

5 It is normally not possible to consume oil or coal-oil mixtures having a water content, as the free water is apt to extinguish the flame.

According to the present invention water is added to a mobile or liquid fuel by emulsification therewith, whereby eflicient combustion can be obtained and moreover, it has been found that under certain conditions the intensity of combustion is increased.

Various emulsifying agents may be used, such as starch or casein. Either an oil soluble or a water soluble emulsifying agent or both conjointly may be used, such as a sulphonic acid derived from a vegetable oil or a naphthenic acid.

Where the fuel is to be used, for instance, in marine work, it will be desirable to use an emulsiher which will operate in the presence of salt or solutions of electrolytes, so that the water content of the fuel will be maintained in emulsification with the fuel in spite of accidental association of the fuel with sea-water or condensed steam.

In the application of the invention to coal-oil mixtures or the like the water may conveniently be added as part of the stabilizer for the suspension of the coal particles in the oil where such is employed.

Combustion controlling agents, such as boron compounds, may be added and these, if water soluble, may be dissolved in the water addition to the fuel. If desired, non-soluble combustion catalysts, such as one of the oxides of iron may be added to the fuel by suspension therein by means of a stabilizing agent which in coal-oil mixtures may be the same stabilizing agent as used for the coal particles.

Intimate emulsification may be obtained by passing the oil with water, or coal dust with oil and water, through a mill, preferably a high speed attrition mill, or a number of such mills in series, which in the case of a coal-oil fuel may also serve to reduce the coal particles to finer size.

In the case of a coal-oil fuel the coal may be subjected to grinding with water as a preliminary step prior to treatment for removal of ash forming constituents by any known system, such as for instance, by means of a centrifuge but preferably by a froth flotation process. By this means a substantially ash-free fuel can be obtamed which has a high water content, and yet sumed. For this purpose materials may be added, 10

such as naphthalene.

By reason of the intimate distribution by means of emulsification of the water throughout the mobile fuel, it will be found that where the fuel is being consumed in a burner this will remain clean, as the dissociation of the water will prevent the partial combustion of the hydrocarbons of the oil or coal and thus prevent the deposit of coke on the burner.

It has been found that the efliclency of combustion is remarkably increased by the addition of water to oil or oil-coal stabilized mixtures according to the present invention, as the following comparative tests, taken purely by way of example, will show.

A single flue boiler having a rated capacity of 3,000 to 3,500 lbs. of steam per hour and roughly 12 ft. 6 ins. by 6 ft. in size was fired with untreated petroleum oil having a viscosity of 500 7 seconds on a No. 1 Redwood viscometer.

Specific gravity at units per pound Duration of test 9 P. M.

to 4 A. M 7 hours Quantity of water evaporated 4660-3566 gallons Temperature of feed water Weight of water used Pounds of steam gener- 51" Fahrenheit 10940 pounds weight ated 1563 pounds weight Quantity of oil consumed 86.0-42 inches Capacity of tank 1-2547 gallons Average temperature of oil 180 Fahrenheit Specific gravity of oil 0.947 5 Specific gravity of oil at 180 Fahrenheit 0.899 Weight of oil used 1008 pounds weight Calorific value of oil 18,900 per poun d weight Weight of water evaporated per pound oil 10.86 pounds Evaporation from and at 212 Fahrenheit 13.03 pounds Steam pressure of boiler- 100 lbs/sq. in gauge Total heat used per lb.

The CO2 content of the flue gases was practically constant throughout the run and varied from 11% to 12% except for the iew minutes occupied in changing the burners.

The average mean temperature throughout the test was 1280 centigrade.

eighth of 1% of starch as emulsifier was then consumed under identical conditions with the following result:-

Duration of test 6 hours (10.30 P. M.- 6.30 P. M. Quantity of water evaporated 1282541255 gallons Temperature of feed water 57 Fahrenheit Weight of water used 15700 pounds Weight of steam generated/hour 1962 pounds Quantity of oil consumed 80-17375" Capacity of tank Average temperature of An oil emulsified with 4% of water using oneoil Specific gravity of oii Specific gravity of oil Weight of oil used Weight of water evaporated per pound of oil- Steam gauge pressure 69 Evaporation from/and at 212 Fahrenheit Calorific value of i.'uel

Total heat used per pound steam Corrected with f e e d water at 64 Fahrenheit British thermal units used in evaporating 10.9 lbs. water Actual efliciency 161 Fahrenheit .907 at 161 Fahrenheit 907 at 161 Fahrenheit 1440.5 pounds 10.9 pounds 94 pounds per square inch 13.00 16,710 British thermal units/pound 1188 British thermal units 1163 British thermal units 7 CO: in flue gases 10% The average mean temperature was found throughout this test to be 1300 centigrade. Moreover, it was found that, while with the u treated or dry oil it was necessary to clean the burners every four hours owing to the considerable quantity of coke deposit forming beneath the flame, with the burners using the treated oil, that is to say, the oil containing the water, only about half the amount of coke deposit had accumulated on the burners after six hours, as compared with the previous accumulation in four hours.

A third test under identical conditions was effected with the same basic medium; that is to say, Anglo-American Petroleum oil havinga viscosity of 500 seconds on No. 1 Redwood viscometer, four parts of water being added emulsified by means of one eighth of one part of starch together with three eighths of one part of borax or boric acid in solution in the water and three eighths of one part of sodium chloride in solution in the water, per hundred parts by weight of oil.

It may here be stated that sodium chloride whilst normally acting as a combustion retarding agent is believed to have a retarding efiect solely upon the rate of combustion, whilst the boron compound addition has a remarkable eifect in increasing the intensity of combustion. This test has had as a result:-

Duration of test 4 hours 3 p. m. to 7 p. m. Quantity of water evaporated 18703-17908 gallons Temperature of feed water Fahrenheit Weight of water used 7950 pounds Weight of steam generrated/hour 19875 pounds Quantity of oil consumed 29.36"

The average mean temperature was 1320 centigrade.

It can readily be ascertained that similar tests with stabilized coal-oil mixtures having a water content and stabilized coal-oil mixtures having a water content together with combustion proinoting agents would give similar results in increase in efliciency.

Satisfactory combustion has been obtained with 1' '-2.547 8 gallons 140 Fahrenheit 683.5 pounds 11.63 pounds 90 pounds oil and oil-coal stabilized mixtures with the water content as high as 10%, although in such cases the combustion efliciency would not be as high as with a lower water content. It will however. be

appreciated that a considerably cheaper fuel can be obtained by this means giving equivalent eflisolved therein a compound of the group consisting of boric acid and water-soluble borates for controlling the combustion and said water component also having therein an emulsifying and stabilizing agent of the group consisting of starch and casein and characterized by being operative in the presence of electrolytes.

2. A liquid fuel comprising an emulsion of fuel oil with water, said water component having dissolved therein boric acid for controlling the combustion and an emulsifying and stabilizing agent of the group consisting of starch and casein and characterized by being operative in the presence of electrolytes.

3. A liquid fuel comprising an emulsion of fuel oil with substantially 4% of water, said water component having dissolved therein a watersoluble boron-oxygen compound for controlling the combustion and an emulsifying agent of the group consisting of starch and casein and char acterized by being operative in the presence of electrolytes, the total quantity of boron-oxygen compound and emulsifying agent being substan tially one-half of 1% by weight of the emulsion, and particles of powdered coal suspended in'the emulsion. t

ARTHUR A. ROBERTS. 

